Solitary cutaneous myofibromas in adults: report of six cases and discussion of differential diagnosis

Penile Myointimoma: A Clinicopathologic Study of 4 Tumors

Penile myointimoma is a rare, benign tumor occurring within the corpus spongiosum vasculature of the glans penis. Thus far, there have been twenty-three reported tumors in the literature. We present four additional tumors of this unique myointimal proliferation. Patients ranged in age from 20 to 68 years and presented with a firm mass on the glans penis. All four tumors displayed distinctive morphologic features consisting of a myointimal proliferation with plexiform architecture of bland myofibroblastic cells in a myxoid background in the corpus spongiosum vasculature. Characteristic cytoplasmic immunoreactivity of lesional cells with smooth muscle actin in addition to a desmin positive collarette of native vessel smooth muscle was seen in all four tumors. No disease was reported in any of the patients at last clinical follow-up (9 months to 15 years) after biopsy or excision. Myointimoma is part of a rare group of mesenchymal tumors that has been recently classified by its distinctive location, morphology, and immunohistochemical reactivity. For any nodular, spindle cell lesion of the corpus spongiosum, myointimoma should be included in the differential diagnosis given its unique characteristics and favorable clinical outcome.

Congenital myofibroma of the skin mimicking a piloleiomyoma

Myofibroma is an uncommon benign soft tissue disorder, which is usually congenital or present in early infancy. Myofibroma usually manifests as a single mass. When there are multiple lesions, the term myofibromatosis is used. The characteristic histopathological feature of the myofibroma is the coexistence of two distinct areas. One area mainly contains plump spindle cells with thin blunt-ended nuclei and eosinophilic cytoplasm, thus indicating myoid characteristics. The other area contains either round or polygonal cells with slightly pleomorphic, hyperchromatic nuclei or small spindle cells typically arranged around a distinct hemangiopericytoma-like vascular pattern. In the present case, the majority of the tumor was composed of the plump myoid spindle cells. This led to an initial diagnosis of a piloleiomyoma. However, the tumor cells were not immunohistochemically positive for desmin. Moreover, careful examination revealed a hemangiopericytoma-like vascular pattern characterized by the presence of high cellular areas with irregular vascular spaces. These features led to the final diagnosis of the myofibroma. It is therefore important to recognize the leiomyoma-like variants of myofibromas.

A unique case of multiple dermatomyofibromas

We report on a case of multiple dermatomyofibromas on the posterior neck of a 10-year-old boy. Dermatomyofibroma is a benign proliferation of myofibroblasts of the skin. It is more common in adolescents and young adults, with a female preponderance. It usually appears as a single plaque or nodule. To our knowledge, this is the first case of multiple dermatomyofibromas reported in the literature.

Myopericytoma: report of two cases associated with trauma

Myopericytoma is a rare, recently described tumor demonstrating a hemangiopericytoma-like vascular pattern. We present two cases of myopericytoma associated with trauma: a 64-year-old man who developed several nodules on his nose four months after sustaining multiple abrasions to his forehead and nose, and a 72-year-old woman with a solitary growth in the alveolar ridge of unknown duration. Biopsy specimens of the lesions in both cases demonstrated a striking concentric perivascular proliferation of bland spindle-shaped pericytic cells characteristic of myopericytoma. Despite sharing morphologic features with angioleiomyoma, myofibroma and glomus tumor, myopericytoma is thought to represent a distinct perivascular myoid neoplasm of skin and soft tissues. The tumor is characterized by a radial and perivascular arrangement of ovoid, spindled to round neoplastic cells that are immunoreactive to alpha-smooth muscle actin, often for h-caldesmon as well as smooth muscle myosin-heavy chain, and usually negative for desmin antibodies. Most cases of myopericytoma are benign, however, local recurrence and malignancy have recently been reported, Myopericytoma can be multifocal involving a single or multiple anatomic regions, and tends to occur in dermal and superficial soft tissues of adults primarily on the extremities. Our cases are unusual examples of myopericytoma manifesting as multiple nodules on the nose, and a solitary growth on the buccal mucosa after trauma.

Perivascular myoma of myopericytoma and myofibromatosis-type arising in a chronic scar

We describe a case of a cutaneous perivascular myoma with features overlapping between the myofibromatosis and the myopericytoma type. The patient is a 58-year-old woman with a painless plaque-like and multinodular lesion in the pretibial dermis and subcutaneous tissue. She had repeated trauma to this site, first in her early youth that left an area of hyperpigmentation, and then again at age 40. The biopsy showed a biphasic pattern with a myofibromatosis-type component composed of spindle cell myoid nodules and more cellular round cell areas. The myopericytoma-like areas appeared to be infiltrating along vessels. These areas contained aggregates of immature-appearing cells arranged concentrically around vascular lumina in a manner reminiscent of pericytes. Immunohistochemical stains showed focal positivity for smooth muscle actin. Immunohistochemical and ultrastructural studies have showed these pericyte-like cells to be of a myoid origin. The reason for the neoplastic proliferation of perivascular myoid cells is presently unknown. The association of trauma and neoplastic transformation of the skin is rare. We report the first case of a cutaneous perivascular myoma arising in a chronic scar.

Myopericytoma: a unifying term for a spectrum of tumours that show overlapping features with myofibroma. A review of 14 cases

BACKGROUND

Myopericytoma (MPC) is a recently proposed term to describe a group of tumours that originate from perivascular myoid cells and show a range of histological growth patterns. Only a small number of series describing MPC have been reported. MPC is frequently misdiagnosed as a sarcoma.

AIMS

To document the clinical and histopathological findings of a series of MPCs, to describe the range of growth patterns and morphological spectrum, and to compare MPC with myofibroma (MF).

PATIENTS/METHODS

Fourteen patients with features of MPC and/or MF were identified from the archival files of the department of anatomical pathology, Royal Prince Alfred Hospital, Sydney, Australia.

RESULTS

There were six female and eight male patients. The mean and median patient ages were 37 and 35.5 years, respectively. The tumours were located in the skin, subcutis, or superficial soft tissues of the distal extremities (13 patients) or the head and neck region (one patient), and showed a spectrum of morphological appearances. They were divided into two groups based upon the predominant growth pattern corresponding to MPC (seven cases) and MF (seven cases). The feature most suggestive of MPC was the presence of a concentric perivascular arrangement of plump spindle shaped cells. The presence of a zonation/biphasic appearance was most characteristic of MF.

CONCLUSIONS

MPC exhibits a spectrum of growth patterns that overlap with MF. Tumours can be designated as MPC or MF depending on the predominant growth pattern.

Myofibroma of the Cheek: A Case Report

Myofibromas are benign mesenchymal tumors that are commonly found in the dermis and subcutaneous tissues of the head and neck. Although most lesions are recognized daring infancy and early childhood, several cases have been reported in older children and adults. We describe the case of a 9-year-old girl who presented with a solitary nodule in the left cheek and a history of minor trauma. Preoperative imaging detected the presence of a subcutaneous soft-tissue mass consistent with a soft-tissue neoplasm rather than a hematoma. Analysis of fine-needle aspiration material was nondiagnostic. Incisional biopsy revealed that the lesion was a myofibroma.

Intravascular myopericytoma

BACKGROUND

Myopericytoma is a benign tumor composed of cells that show apparent differentiation towards putative perivascular myoid cells called myopericytes. It arises most commonly in the dermis or subcutaneous tissue of the extremities in adults.

METHODS

We describe a myopericytoma that was unusual in its intravascular location.

RESULTS

A 54-year-old man presented with a 10-year history of a painful slowly growing 1.5-cm nodule in the subcutaneous tissue of the thigh. Histologic examination of the excised lesion showed that is was entirely contained within the lumen of a vein. It was composed of a proliferation of myoid-appearing spindle cells, which were arranged in a striking concentric pattern around numerous blood vessels, in a manner that accentuated the vessel walls. This pattern is characteristic of myopericytoma. In some areas, fascicles of spindle cells, embedded in a myxoid stroma, bulged into the lumina of lesional vessels, reminiscent of myofibroma/myofibromatosis. Lesional spindle cells were diffusely positive for smooth muscle actin, focally positive for CD34 and were negative for desmin, cytokeratin, S100 protein, HMB-45 and CD31.

CONCLUSION

This case illustrates that myopericytoma can be entirely intravascular in its location.

Adult acral cutaneous myofibromas in a patient with generalized morphea

Myofibroma is the term for a group of solitary or generalized soft tissue tumors that may be located in the skin or within skeletal muscle, bone, and viscera. These tumors occur most commonly in children. However, examples of myofibroma have been reported in adults, in whom they usually present as solitary lesions of the head and neck, trunk, and extremities. "Cutaneous nodules" have been reported in both localized and systemic scleroderma, but to our knowledge, there are no specific reports of myofibromas developing in this patient population. We report a case of acral myofibromas in a patient with generalized cutaneous morphea. This occurrence is of interest in view of the possible role of myofibroblasts in the pathogenesis of scleroderma.

Cutaneous smooth muscle neoplasms: clinical features, histologic findings, and treatment options

Cutaneous smooth muscle is present in 3 separate locations: arrector pili muscles, blood vessel walls, and genital/areolar skin. Benign or malignant smooth muscle neoplasms may arise from each of these locations. This review discusses the pathogenesis, clinical manifestations, histologic findings, prognosis, treatment options, and controversial areas of cutaneous smooth muscle neoplasms. ( J Am Acad Dermatol 2002;46:477-90.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be able to discuss the pathogenesis, clinical manifestations, histologic findings, prognosis, and treatment options of cutaneous smooth muscle neoplasms.

Perivascular myoma: case report with immunohistochemical and ultrastructural studies

A subcutaneous myopericytoma-type perivascular myoma arising in the elbow of a 61-year-old woman is described. The tumor was well demarcated and consisted microscopically of small ovoid and spindle cells arranged in a concentric fashion, surrounding small to medium-sized vessels and imparting a superficial resemblance to hemangiopericytoma. In some areas, the cellular whorls were separated by myxoid stroma. Cells located between cellular whorls appeared immature with scant cytoplasm but did not show distinct nuclear anaplasia, increased mitoses or foci of necrosis. Immunohistochemistry showed that constituent cells were positive for alpha-smooth muscle actin and desmin. Electron microscopy disclosed that the immature-looking cells, as well as the ovoid and spindle-shaped cells, possessed focal densities along with thin filaments, subplasmalemmal densities, pinocytotic vesicles and an external lamina. These ultrastructural and immunohistochemical features indicate a myoid nature of pericytic cells and justify this type of neoplasm being categorized as perivascular myoid tumor.

A distinctive myointimal proliferation ('myointimoma') involving the corpus spongiosum of the glans penis: a clinicopathologic and immunohistochemical analysis of 10 cases

This study details the clinicopathologic and immunohistochemical features associated with 10 cases of a distinctive myointimal proliferation involving the corpus spongiosum of the glans penis. Patients ranged in age from 2 to 61 years old (mean age, 29 yrs) and presented with a mass that varied in size from 0.5 to 1.9 cm in greatest dimension. The process was said to be present from 4 days to more than 6 months before surgical intervention. In each case, microscopic examination revealed almost identical histology. There was a prominent, often occlusive, fibrointimal proliferation with plexiform architecture involving the vasculature of the corpus spongiosum. The proliferation consisted of stellate-shaped and spindled cells embedded in abundant fibromyxoid matrix. Occasional lesional cells had well-developed myoid characteristics with moderately abundant eosinophilic cytoplasm, blunt-ended nuclei, and juxtanuclear vacuoles. Foci with degenerative changes, including "ghost cell" morphology, were also present. The myointimal process was extensively immunoreactive for alpha-smooth muscle actin, muscle-specific actin (HHF-35), and calponin, but it was minimally reactive for the D33 and D-ER-11 desmin clones. In contrast, native vascular smooth muscle encompassing the proliferation was strongly immunoreactive for all five markers. The myointimal cells were nonreactive for CD34, S-100 protein, and keratin. Factor VIIIrAg, CD31, and CD34 highlighted intact endothelial cells lining suboccluded vessels, scattered capillaries that penetrated the proliferation, and the normal uninvolved vasculature. The examined specimens were punch, incisional, or excisional biopsies, and in each instance, the process microscopically extended to the tissue margin. Follow-up data are available for 8 cases (median follow-up interval, 5 yrs 8 mos): one incompletely excised lesion with 6 months follow-up is stable but persistent, one lesion with 10 years follow-up regressed spontaneously after a punch biopsy, and the remaining six lesions have not recurred. A differential diagnosis of myofibroma, late-stage intravascular (nodular) fasciitis, vascular leiomyoma, and plexiform fibrohistiocytic tumor is discussed.